Power Failure Sensing Device and a Card Reader Having a Power Failure Sensing Device

1. A power failure sensing device comprising: a power failure sensing circuit which outputs a power failure sensing signal to an internal electrical power source of a use apparatus provided to interlock an external device when an output voltage from an internal electrical power source falls below a predetermined level, wherein, said power failure sensing circuit of said use apparatus provides an outside signal input part receiving a power failure signal from said external device and; a power failure signal output part which outputs a final power failure sensing signal in response to at least one signal of an external power failure signal and an interior power failure signal, wherein said external power failure signal is generated from said outside signal input part when said external device has a power failure, said interior power failure signal being generated when said use apparatus has a power failure, wherein said use apparatus is a card reader and said external device is a host device which controls the card reader, the card reader is provided with an internal electrical power source and an outside signal input part which receives a power failure signal in the host device, wherein the card reader outputs a final power failure sensing signal in response to at least one of the power failure signal in the host device, which controls the card reader, and the internal power failure signal of the internal electrical power source of the card reader.

2. A method for a card reader having a power failure sensing device compromising the steps of: providing a power failure sensing circuit which outputs a internal power failure signal from an internal electrical power source of a card reader provided to interlock a host external device when an output voltage from said internal electrical power source falls in less than a predetermined level; providing an outside signal to an input part which receives a power failure signal from said host external device and which may output an external power failure signal to a power failure signal output part; outputting from a power failure signal output part a final power failure sensing signal in response to at least one signal of said external power failure signal or said internal power failure signal; providing the card reader with an internal electrical power source and an outside signal input part which receives a power failure signal; and outputting a final power failure sensing signal in response to at least one of the power failure signal in the host device, which controls the card reader, and the internal power failure signal of the internal electrical power source of the card reader.

3. The power failure sensing device of claim 1 wherein the card reader provides said output part uses an open collector type output circuit.

4. A power failure detection system for detecting power failures in a cash dispenser machine and in an associated card reader comprising: an external signal input part for receiving a power failure signal from a first power failure sensing circuit located in a host cash dispenser machine; a card reader associated with the cash dispenser; an internal power source located in said card reader; a second power failure sensing circuit located in said card reader; and, a power failure signal output part for receiving and processing power failure signals from said external signal input part and from said second power failure sensing circuit, said power failure signal output part further including circuit to output a final power failure signal if either said card reader or said cash dispenser has a power failure and the shape of said final power failure signal indicates whether the card reader or the cash dispenser or both experience a power failure, wherein the card reader is provided with an internal electrical power source and an outside signal input part which receives a power failure signal in the host device.